A conventional lighting-knob-switch is described by referring to FIG. 8 and FIG. 9. FIG. 8 is a cross section and FIG. 9 is a perspective exploded view of the conventional lighting-knob-switch. In those drawings, a knob 1 made of plastic is engaged with a light conductor 2 made of plastic disposed at the back of the knob 1. A protrusion 2A for lighting disposed at the center of the light conductor 2 is inserted into a center hole 1A of the knob 1. A plate 3 on which a character of the switch mode is drawn is mounted to the protrusion 2A for lighting.
A back-free type box case 4 houses a rotor 5 rotatively, and a first terminal plate 6 is disposed at an open back of the case 4. In front of the first terminal plate 6, a plurality of fixed points 7 are disposed. A rotative shaft 6A, which is a front part of a rotor 5, extends through a hole 4A punched on the front end of the case 4, and a tip of the rotative shaft 5A is engaged and secured with a rotative shaft 2A of the light conductor 2. A press spring 8 and a contact reed 9 are mounted to a back of the rotor 5, where the contact reed 9 is forced to touch elastically the fixed contacts 7 by the press spring 8. A light emitter 10, such as a small bulb or a light emitting diode, is mounted to the back of the light conductor 2. A second terminal plate 11 on which a connector 12 and other electric parts (not shown) are mounted is disposed on a rear side of the bottom plate of the case 4. An elastic lead wire 13 couples the light emitter 10 to the second terminal plate 11, and its center part coils around the rotative shaft 2B in several turns for allowing a rotation of the conductor 2 and the knob 1.
In the above structure, when the knob I is turned, the rotative shaft 2B rotates the rotor 5 via the rotative shaft 5A, and the contact reed 9 mounted on the back of the rotor 5 is forced to elastically touch the fixed contacts 7 and rotates, thus an electrical contact between the plurality of fixed contacts 7 is on and off due to the elastic rotation.
When an electrical signal from an apparatus (not shown) is fed into the light emitter to turn it on via the connector 12, the electrical signal runs through the lead wire 13 and turns on the light emitter 10. The entire light conductor 2 is lit by illumination from the light emitter 10. The light running through the protrusion 2A lights up the switch mode character on the plate 3.
In the above conventional structure, the luminance of the protrusion 2A is likely to be uneven depending on a size of the light conductor 2, because the light emitter 10 mounted at periphery of the light conductor 2 lights up the entire light conductor 2, and thereby illuminating the protrusion 2A. In addition, the center part of the lead wire 13 are coiled around the rotative shaft 2B in several turns, which causes difficulties as well as takes an extra time in an assembly work.